Click on the Spam filters link in the Mail Menu area.
Click on the 
button next to the spam filter that you want to delete. Click on the Spam filters link to return to the Spam Filters window to confirm that it has been deleted.
Delete a spam filter when you no longer need it. There is no way to modify a spam filter - if you have made a mistake, simply delete the filter and start again.
To delete a spam filter:
Click on the Spam filters link in the Mail Menu area.
Click on the button next to the spam filter that you want to delete. Click on the Spam filters link to return to the Spam Filters window to confirm that it has been deleted.